I'm trying to wire up a flash chip using the extension port on the back of a Turbo Graphics 16. It looks like it has full access to all the pins on the HuCard connector so it should work in theory. The schematic I'm using for a reference has an 29f800 instead of my 29f016. The only difference is the 29f800 has a line called q-15/a-1 connected to A0 of the HuCard connector and the 29f016 has no such pin. Instead I just wired up A0 to pin A0 and so on up to A19. Would that be correct or should have I skipped A0 on the cart connector and started with a1 going to a0 on my 29f016?

Sounds like an interesting project, let us know how it goes. Yes, A0 to A0 would be correct, as the 29F016 is an 8-bit ROM. 29F800 is 16-bit, so the addresses are intended for 16 bits at a time. It has an 8-bit mode too, in that case you use address "negative one" for that lowest bit.

I do agree this project sounds very interesting but what exactly is it supposed to do?? Should this memory work as read-only-memory for TG16 or should it work like a pendrive for TG16?? Also, what machine are you planning to use?? Since I see some differences between these 2...

As long as I can see, the actual data bus of TG16 is 8bit wide so there's no reason to ever use a 16bit memory and messing up with decoders or /BYTE pins, just simply use an 8bit memory and that's it.

But what baffles me the most is that what exactly does A20 line do?? It is highlighted as "system functions" instead of "address bus" but it actually is highlighted yellow on the 2nd pinout.... As long as I can see, you can easily use a 27C080/29F080 on both cases for sure but I'm not exactly sure if it can handle a 29F016 as well. In the first case, A20 is described as "A20 is often used as CE - Chip Enable" and at the same time, there's a clarification "As far as I know all the system functions are active-low".

This would mean A20 is actually /A20 so you'll need some kind of inverter or divide the entire data into halves and swap them. So is "A20" actually A20, or is it /A20 or CE or maybe /CE???

Also, the 2nd pinout has a /OE pin while the first one doesn't have that. This is also very interesting.... This means the 2nd console is controlling the output gates in memory while the 1st one doesn't?? There's too much confusion around that

Alright understood, thanks for that info Memblers. This is just trying to interface a flash chip to act as a ROM in a non intrusive way MaarioS. As for the A20, yeah it's weird, but it's really /CE.

Earlier today I realized that the EXT pinout is for the PC Engine, and the TG16 pins differ in that the d0-d7 lines are reversed. I swapped those and double checked all my wiring, but it's still giving me trouble. It's probably something simple I'm just forgetting and will come back to it in a day or two with a fresh slate.

Alright understood, thanks for that info Memblers. This is just trying to interface a flash chip to act as a ROM in a non intrusive way MaarioS. As for the A20, yeah it's weird, but it's really /CE.

Earlier today I realized that the EXT pinout is for the PC Engine, and the TG16 pins differ in that the d0-d7 lines are reversed. I swapped those and double checked all my wiring, but it's still giving me trouble. It's probably something simple I'm just forgetting and will come back to it in a day or two with a fresh slate.

A20 is used as /CE for hucards. The upper address range was supposedly reserved for rear bus addons, so A20 was a cheap way to handle this. But you don't have to. There's plenty of open bus areas that can be access from both the hucard port and the back plane, equally. The Arcade Card (both versions), maps some hardware registers into the $1FFA00-1FFAFF range (from the hucard port), as well as mapping two byte registers mirrored into 8k banks ($80000-87FFF). There's also a hucard detect 'pin', which is used to enable/disable lower mapped ram/rom/etc to the lower range depending if a hucard is present (this can be controlled via the hucard port; the later game express cards do this to access superCD ram, but still use its own rom - IIRC), though the reaction of that pin status is directly handled by whatever rear bus addon.

Tried to mess with this again lately and got it too work. MaarioS was right. The EXT pinout online in the tg16 service Manuel is different than what the hucard pin out reads. Had to open it up and test each pin on the hu card connector and eventually got it to start the game.

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